there are a reference documentation troube like 5.12:
reference documentation cannot open:
Server error
The website encountered an error while retrieving http://localhost:8000/doc/live/refere.... It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this webpage later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.

5.12 can open thematic_tutorials and find reference documentation ,but 5.13 cannot open
Server error
The website encountered an error while retrieving http://localhost:8000/doc/live/themat.... It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this webpage later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.